A bullet of mass 30 g is fired from a pistol of 2 kg with a horizontal velocity of 150m/s what is the recoil velocity of the gun

mA = 30 g = 0.03 kg
mB = 2 kg
uA and uB = 0 m/s
vA = 150 m/s
initial momenta = mAuA +mBuB
                         = 0.03*0 + 2*0
                         = 0 m/s
final momenta = mAvA + mBvB
                        = 0.03*150 + 2*v
                        = 4.5 + 2v
according to law of conservation of momentum,
    initial momenta = final momenta
4.5+2v = 0
v = -4.5 - 2
final recoil velocity = - 6.5